Solvent composition and water-repellent/oil-repellent composition using the same

ABSTRACT

Provided is a nonflammable solvent composition comprising 40% by volume or more of a non-flammable perfluoro organic compound.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a novel nonflammable solvent composition having excellent characteristics as a solvent which can take the place of 1,1,2-trichloro-1,2,2-trifluoroethane (hereinafter abbreviated to "CFC-113"), and furthermore, it relates to a fluorine-based water-repellent/oil-repellent composition using the above-mentioned solvent composition and having water-repellent/oil-repellent properties, lubricating properties, mold release properties and the like.

2. Related Background Art

Most of chlorofluorocarbons (hereinafter abbreviated to "CFCs") are less toxic, incombustible and chemically stable, and various kinds of CFCs having different boiling points are available and therefore they have been utilized in many industrial fields. Above all, CFC-113 has been used as a degreasing solvent, a dispersant and a diluting solvent for a plastic material, a part of rubber materials and various composite materials by the utilization of its specific chemical characteristics.

In recent years, ozone holes which are due to unusual changes of earth environment have been discovered, and it has been elucidated that its main cause is organic chlorine-based compounds. Particularly chemically stable CFC-113 has a long life in the troposphere, and it diffuses and reaches the stratosphere. In the stratosphere, CFC-113 gives rise to photolysis under the influence of sunbeams to generate chlorine radicals. The thus generated chlorine radicals combine with ozone, so that an ozone layer is broken. Accordingly, the use of the organic chlorine-based compounds inclusive of the CFCs will be globally restricted and forbidden in the future. Among others, CFC-113 has a high ozone destruction coefficient, and hence its prompt replacement is desired and a severe schedule of reducing the employment of CFC-113 is justified.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a novel solvent composition replaceable with CFC-113 which has been heretofore used in such circumstances.

Another object of the present invention is to provide a solvent composition suitable as a degreasing solvent for various substrates.

Still another object of the present invention is to provide a water-repellent/oil-repellent composition suitable as a modifier for the surfaces of various substrates.

The present invention for achieving the above-mentioned objects is directed to a nonflammable solvent composition containing 40% by volume or more of non-flammable perfluoro organic compound, and a nonflammable water-repellent/oil-repellent composition containing a fluorine-containing polymer and a solvent containing 40% by weight or more of a non-flammable perfluoro organic compound.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The reasons why CFC-113 has often been used as a decreasing solvent are

(a) that it has a suitable solubility to various soils and oils,

(b) that It is excellent in chemical stability, and there is no worry of decomposition and the like,

(c) that it is less toxic and has neither a flash point nor an ignition point, and thus its operational safety is high, and

(d) that its polarity is low and it does not damage various plastic materials.

Therefore, in order to take the place of CFC-113, similar characteristics are required. Nowadays, as the hydrochlorofluorocarbon (HCFC), there have been developed hydrochlorofluorocarbons such as 1,1-dichloro-2,2,2-trifluoroethane (hereinafter abbreviated to "HCFC-123"), 1-fluoro-1,1-dichloroethane (hereinafter abbreviated to "HCFC-141b"), 1,1-dichloro-2,2,3,3,3-pentafluoropropane (hereinafter abbreviated to "HCFC-225ca") and 1,3-dichloro-1,1,2,2,3-pentafluoropropane (hereinafter abbreviated to "HCFC-225cb"), and their substitution has been investigated.

However, most of these Hydro Chloro Fluoro Carbons have high solubility to various oils and fats but tend to attack substrates, particularly, general-purpose plastics such as acrylic resins and ABS resins, and therefore they are not considered to be all-round substitutes of CFC-113.

In order to satisfy the above-mentioned necessary properties, much attention is paid to perfluoro organic compounds having less chemical attack properties, and various kinds of solvent compositions have been intensively investigated. As a result, the present invention has been attained. That is, the solvent composition which can be used in the present invention contains a non-flammable perfluoro organic compound which has an extremely low polarity and no decreasing ability and which does not damage various substrates at all. In view of requirements of having no flash point, having a high vapor pressure, having a high chemical stability and having a reduced chemical attack to various materials, there can be suitably used perfluoroalkanes, perfluorocycloalkanes, perfluoro ethers, perfluoro cycloethers and the like as the perfluoro organic compounds which are used in the present invention.

Furthermore, the perfluoro organic compounds which can be used in the present invention preferably have a vapor pressure of 30 Torr or more at 25° C.

Typical examples of the perfluoro organic compounds include perfluoropentane (C₅ F₁₂), perfluorohexane (C₆ F₁₄), perfluoroheptane (C₇ F₁₆), perfluorooctane (C₈ F₁₈), perfluorocyclohexane (C₆ F₁₂), perfluorocycloheptane (C₇ F₁₄), perfluoro(alkylcyclohexane) (C₇ F₁₄ and C₈ F₁₆) and perfluoro(2-butyltetrahydrofuran) (C₈ F₁₆ O). The content of each of these perfluoro organic compounds is preferably 40% by volume or more based on the volume of the solvent composition of the present invention. When the content of the perfluoro organic compound is less than the above-mentioned amount, a flash point appears, and in the case that the compound is used in the form of a mixture with another flammable organic compound, the chemical attack of the flammable organic compound on products takes place inconveniently.

When the solvent composition of the present invention is used as the above-mentioned decreasing solvent, an organic compound having a degreasing power, particularly a flammable organic compound is added to the solvent composition.

This flammable organic compound having the degreasing power is required

(1) to be miscible with the perfluoro organic compound,

(2) to have a suitable dissolving power (the degreasing power) to various soils and oils, and

(3) to have a less chemical attack to products (particularly general-purpose plastics).

Examples of the particularly preferable organic compound which can meet the above-mentioned requirements include ether compounds, alkanes and cycloalkanes.

Preferable typical examples of the ether compounds include compounds represented by the formula

    R.sub.1 --O--R.sub.2

wherein R₁ is C_(n) H_(2n+1) or --Si (CH₃)₃, R₂ is C_(m) H_(2m+1) or --Si(CH₃)₃, and n and m meet 1≦n, m≦4, and 2≦n+m≦6.

Preferable typical examples of the alkanes and cycloalkanes include compounds represented by the formulae

    C.sub.P H.sub.2p+2 and C.sub.q H.sub.2q

wherein p and q meet 5≦p and q≦8.

In order to satisfy the above-mentioned requirements (2) and (3), a particularly preferable embodiment is to use an organic compound having a solubility parameter (an SP value) of 7.5 or less. The SP values can be directly calculated from evaporation latent heat or vapor pressure, but in this specification, literature values mentioned in POLYMER HANDBOOK, 2nd Edition are employed and they are as follows (the values in parentheses were calculated in accordance with an intermolecular attraction constant method of Small). Preferable typical examples of such organic compounds are as follows:

    ______________________________________                                         n-pentane             SP value = 7.0                                                                 (7.2)                                                    n-hexane              SP value = 7.3                                                                 (7.3)                                                    2-methylpentane (isohexane)                                                                          SP value = (7.1)                                         2-methylhexane (isoheptane)                                                                          SP value = (7.2)                                         2,2,4-trimethylpentane (isooctane)                                                                   SP value = (6.8)                                         hexamethyldisiloxane (C.sub.8 H.sub.18 OSi.sub.2)                                                    SP = (6.0)                                               diethyl ether (C.sub.4 H.sub.10 O)                                                                   SP = 7.4 (7.3)                                           diisopropyl ether (C.sub.6 H.sub.14 O)                                                               SP = 7.0 (6.9)                                           methyl tert-butyl ether (C.sub.5 H.sub.12 O)                                                         SP = (7.2).                                              ______________________________________                                    

Furthermore, the solvent composition of the present invention can be also suitably used as a solvent composition for a water-repellent/oil-repellent agent which can modify the surfaces of substrates, i.e., can protect the substrates from contamination and impart water-repellent/oil-repellent properties to them.

As the solvent for the water-repellent/ oil-repellent agent, 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) has been overwhelmingly used for the reasons of the solubility of a polymer, safety, stability and the like. As other examples of the solvent, there have been used toluene, ethyl acetate and 1,1,1-trichloroethane, but these solvents tend to damage the substrates to be treated. Therefore, restriction is put the selection of the substrates. In addition, most of these solvents are flammable, and therefore safety and the like are insufficient.

According to the present invention, there can be provided a non-ODC (Ozone Depletion Chemicals) type all-round water-repellent/oil-repellent composition which is free from a flash point and which is applicable to the various substrates without the restriction, by the use of a solvent composition containing 40% by weight or more of the above-mentioned non-flammable perfluoro organic compound as a solvent component of the water-repellent/oil-repellent composition.

In order to develop the non-ODC type all-round water-repellent/oil-repellent composition of the present invention which is applicable to the surfaces of the various substrates to be treated, a solute and a solvent are required to have the following characteristics.

Solute

(a) To have a functional group for giving a sufficiently low surface energy, and

(b) to give a sufficient adhesive strength to the various substrates,

Solvent

(a) To have selective solubility only to the solute, and neither to dissolve nor to swell other materials,

(b) to be less toxic, to has neither a flash point nor an ignition point, and thus to have high operation safety, and

(c) to have a high vapor pressure and a high drying rate.

For the purpose of obtaining the water-repellent/oil repellent composition which can meet all of the above-mentioned necessary characteristics, solvent mixtures have been intensively investigated, and as a result, the present invention has been attained.

The solute of the water-repellent/oil repellent composition which is used in the present invention is preferably a fluorine-containing polymer having a long-chain perfluoroalkyl group of C₆ F₁₃ or more as a functional group, and the polymer preferably contains 40 mole % or more of the fluorine-containing vinyl monomer so as to be highly fluorinated. The perfluoroalkyl group of C₆ F₁₃ or more as the functional group is particularly excellent in oil-repellency. In addition, also in the case that the polymer contains 40 mole % or more of the fluorine-containing vinyl monomer, the polymer is particularly excellent in oil-repellency. Typical examples of the solute which can be used in the present invention are as follows.

Homopolymer of 2-(perfluorooctyl)ethyl acrylate, homopolymer of (perfluoroheptyl)methyl methacrylate, homopolymer of 2-(N-ethylperfluorooctasulfoamido)ethyl acrylate, 2-(perfluorohexyl)ethyl methacrylate (60 mole %)/methyl methacrylate (30 mole %)/2-hydroxyethyl methacrylate (10 moles) copolymer, 2-(perfluorooctyl)ethyl acrylate (70 moles)/benzyl methacrylate (25 mole %)/2-hydroxyethyl methacrylate (5 mole %) copolymer, and 2-(perfluoroisononyl)ethyl acrylate (50 mole %)/vinyl acetate (30 mole %)/methyl methacrylate (10 mole %)/2-hydroxyethyl methacrylate (10 mole %) copolymer.

When it is desired to obtain the uniform and flat film, each of the above-mentioned solutes is preferably used in the range of from 0.01% to 5% by weight, more preferably in the range of from 0.05% to 1% by weight, based on the weight of the total components. A solute concentration of 0.01% by weight or more is particularly preferable in that the film having the sufficient oil-repellency can be formed, and at a solute concentration of 5% by weight or less, the uniform film can be obtained due to the solvation of the solute.

Furthermore, as the solvent composition for dissolving the above-mentioned solute which can be used in the water-repellent/oil-repellent composition of the present invention, a solvent for extinguishing a flash point of the total water-repellent/oil-repellent composition of the present invention and for relieving the damage to the substrate is preferable. In fact, the above-mentioned solvent composition of the present invention is suitable. In addition, usual organic solvents and chlorine-based solvents can be also used together with the solvent composition, depending upon kinds of solute and other additives.

Examples of the solvent which can be used together with the solvent composition of the present invention include fluorine-containing solvents, for example, perfluorocarboxylic acid derivatives such as methyltrifluoro acetate, ethyltrifluoro acetate and butylpentafluoro propionate; fluorine-based benzene derivatives such as hexafluorobenzene, pentafluorobenzene, benzotrifluoride and bistrifluoromethylbenzene; fluorine-containing alcohols such as trifluoroethanol, pentafluoropropanol and hexafluorolsopropanol; and hydrochlorofluorocarbons such as HCFC-123, HCFC-141b and HCFC-225.

Optional additives can be added to the water-repellent/oil-repellent composition of the present invention, so long as it has no flash point.

The water-repellent/oil-repellent composition of the present invention can be applied by the use of brush coating, immersion, spin coating, roll coating or spray coating.

EXAMPLES

Now, the present invention will be described in detail in reference to examples.

    ______________________________________                                         Example 1                                                                      Perfluorohexane      55 vol %                                                  Diisopropyl ether    45 vol %                                                  Example 2                                                                      Perfluoropentane     50 vol %                                                  Diethyl ether        50 vol %                                                  Example 3                                                                      Perfluoroheptane     60 vol %                                                  Diisopropyl ether    40 vol %                                                  Example 4                                                                      Perfluorohexane      25 vol %                                                  Perfluoropentane     25 vol %                                                  Isooctane            50 vol %                                                  Example 5                                                                      Perfluorooctane      30 vol %                                                  Perfluoro(butyltetrahydrofuran)                                                                     20 vol %                                                  Isooctane            50 vol %                                                  Example 6                                                                      Perfluorohexane      60 vol %                                                  Methyl tert-butyl ether                                                                             40 vol %                                                  Example 7                                                                      Perfluorohexane      55 vol %                                                  Isohexane            45 vol %                                                  Example 8                                                                      Perfluorohexane      50 vol %                                                  Hexamethyldisiloxane 50 vol %                                                  Example 9                                                                      Perfluoropentane     20 vol %                                                  Perfluorohexane      30 vol %                                                  Methyl tert-butyl ether                                                                             25 vol %                                                  n-hexane             25 vol %                                                  Example 10                                                                     Perfluoropentane     20 vol %                                                  Diisopropyl ether    20 vol %                                                  Isooctane            40 vol %                                                  Comparative Example 1                                                          CFC-113                                                                        Comparative Example 2                                                          CFC-123                                                                        Comparative Example 3                                                          CFC-141b                                                                       Comparative Example 4                                                          CFC-225ca            50 vol %                                                  CFC-225cb            50 vol %                                                  Comparative Example 5                                                          Perfluorohexane      20 vol %                                                  Diisopropyl ether    80 vol %                                                  Comparative Example 6                                                          Perfluorohexane      30 vol %                                                  Diisopropyl ether    60 vol %                                                  ______________________________________                                    

In Table 1, there are comparably shown characteristics of the mixed solvent compositions in the above-mentioned ratios.

Plastic resistance

In order to confirm that bad influences such as dissolution and swelling to general-purpose plastics were not present, a swelling test was made. Test pieces of the used general plastics were as follows.

    ______________________________________                                         PMMA (acryl)      Delpet 80N (Asahi Chemical                                                     Industry Co., Ltd.)                                          PC (polycarbonate)                                                                               Panlight 1225 (Teijin                                                          Chemical Industry                                                              Co., Ltd.)                                                   ABS (acrylonitrile/buta                                                                          Saikorak EX120 (Ube Saikon                                   diene/styrene copolymer)                                                                         Co., Ltd.)                                                   POM (polyacetal)  Juracon M90 (Polyplastic                                                       Co., Ltd.)                                                   PS (polystyrene)  HT53 (Idemitsu                                                                 Petrochemicals                                                                 Co., Ltd.)                                                   Urethane rubber   Mirakutran E585 (Nippon                                                        Mirakutran Co., Ltd.)                                        ______________________________________                                    

The test was made by cutting each test material into test pieces having a size of 25×100, immersing them in each solvent composition of the above-mentioned examples and comparative examples for 1 hour, and then calculating weight changes after the immersion. The test pieces having a weight change of less than 0.1% by weight are represented by o, the test pieces of from 0.1% by weight to 1% by weight are represented by Δ, and the test pieces of 1% by weight or more are represented by x.

Flammability

The flammability was measured in accordance with JIS K2265 by the use of a tag sealing type automatic flash point test machine (ATG-4 type; Tanaka Science Instrument Co., Ltd.).

Degreasing Power

As model contaminants, there were selected a cutting oil (MC-W, Idemitsu Kousan Co., Ltd.) and an anticorrosive oil (Polybutene LV-7, Nippon Petrochemicals Co., Ltd.), and 10 μl of each oil were dropped on a slide glass (25×76×1) to prepare contaminated model works. Each model work was immersed in 50 ml of each solvent composition of the examples and the comparative examples, and then washed with at room temperature for 1 minute by means of an ultrasonic washing machine of 28 kHz and 100 W. After the model work was pulled up, a degreasing power was evaluated at a contact angle of pure water on the model work.

Drying time

10 μl of each solvent composition were dropped on a slide glass, and a time which was taken till a weight change was not observed any more was measured.

ODP

Ozone depletion potentials (ozone destruction coefficient).

                                      TABLE 1                                      __________________________________________________________________________                                  Flash                                                                              Degreasing                                                                            Drying                                        Plastic Resistance    Point                                                                              Power  Time                                          PMMA PC ABS                                                                               POM PS                                                                               Urethane                                                                            [°C.]                                                                       MC-W                                                                               LV-7                                                                              [sec]                                                                              ODP                                __________________________________________________________________________     Example 1                                                                             ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       None                                                                               38  43  7  Absent                             Example 2                                                                             ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       None                                                                               36  41 -2  Absent                             Example 3                                                                             ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       None                                                                               39  44 19  Absent                             Example 4                                                                             ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       None                                                                               36  42 20  Absent                             Example 5                                                                             ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       None                                                                               36  41 50  Absent                             Example 6                                                                             ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       None                                                                               37  43  7  Absent                             Example 7                                                                             ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       None                                                                               35  40  6  Absent                             Example 8                                                                             ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       None                                                                               39  45 22  Absent                             Example 9                                                                             ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       None                                                                               36  41  7  Absent                             Example 10                                                                            ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       None                                                                               35  41 15  Absent                             Comp. Ex. 1                                                                           ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       None                                                                               36  41 28  Present                            Comp. Ex. 2                                                                           x    x  x  x   x x    None                                                                               35  40 10  Present                            Comp. Ex. 3                                                                           x    x  x  x   x x    None                                                                               36  41 10  Present                            Comp. Ex. 4                                                                           x    ◯                                                                     Δ                                                                           ◯                                                                      ◯                                                                    x    None                                                                               36  42 31  Present                            Comp. Ex. 5                                                                           ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       10  35  40  7  Absent                             Comp. Ex. 6                                                                           ◯                                                                       ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                    ◯                                                                       20  37  41  8  Absent                             __________________________________________________________________________

    ______________________________________                                         Example 11                                                                     2-(perfluorooctyl)ethyl acrylate                                                                     0.1%    by weight                                        (70 mole %)/benzyl methacrylate                                                (25 mole %)/2-hydroxyethyl                                                     methacrylate (5 mole %)                                                        copolymer                                                                      Perfluorohexane       90%     by weight (*)                                    Bistrifluoromethylbenzene                                                                            9.9%    by weight                                        Note(*): This amount exceeds 40% by volume.                                    Example 12                                                                     Homopolymer of 2-(N-ethyl                                                                            0.25%   by weight                                        per-fluoro octasulfoamide)ethyl                                                acrylate                                                                       Perfluoroheptane      99.75%  by weight (*)                                    Note(*): This amount exceeds 40% by volume.                                    Example 13                                                                     2-(perfluoroisononyl)ethyl                                                                           1%      by weight                                        acrylate (50 mole %)/vinyl acetate                                             (30 mole %)/methyl methacrylate                                                (10 mole %)/2-hydroxyethyl                                                     methacrylate (10 mole %)                                                       copolymer                                                                      Perfluorohexane       50%     by weight (*)                                    Perfluoro-2-          40%     by weight (*)                                    butyltetrahydrofuran                                                           Pentafluorobenzene    9%      by weight                                        Note(*): Sum of these amounts exceeds 40% by volume.                           Example 14                                                                     Homopolymer of        0.15%   by weight                                        (perfluorohexyl)-ethyl                                                         acrylate                                                                       Perfluorohexane       60%     by weight (*)                                    Perfluoroheptane      20%     by weight (*)                                    Perfluorooctane       10%     by weight                                        Benzotrifluoride      9.85%   by weight                                        Note(*): Sum of these amounts exceeds 40% by volume.                           Example 15                                                                     (Perfluoroalkyl**)ethyl                                                                              0.3%    by weight                                        acrylate (60 mole %)/methyl                                                    methacrylate (30 mole %)/                                                      hydroxyethylmethacrylate (10 moles)                                            copolymer                                                                      (**The perfluoroalkyl group was a mixture of C.sub.4 F.sub.9 to                C.sub.10 F.sub.21, and C.sub.8 F.sub.17 was the main component.)               Perfluorooctane       45%     by weight (*)                                    Perfluoro-2-          45%     by weight (*)                                    butyltetrahydrofuran                                                           Bistrifluoromethylbenzene                                                                            9.7%    by weight                                        Note(*): Sum of these amounts exceeds 40% by volume.                           Comparative Example 7                                                          2-(perfluorooctyl)ethyl                                                                              0.1%    by weight                                        acrylate (70 mole %)/benzyl                                                    methacrylate (25 mole %)/                                                      2-hydroxyethylmethacrylate (5 mole %)                                          copolymer                                                                      CFC-113               99.9%   by weight                                        Comparative Example 8                                                          2-(perfluorooctyl)ethyl                                                                              0.1%    by weight                                        acrylate (70 mole %)/benzyl                                                    methacrylate (25 mole %)/                                                      2-hydroxyethylmethacrylate                                                     (5 mole %) copolymer                                                           CFC-113               90%     by weight                                        CFC-112               9.9%    by weight                                        Comparative Example 9                                                          2-(perfluoroisononyl)ethyl                                                                           1%      by weight                                        acrylate (50 mole %)/vinyl acetate                                             (30 mole %)/methyl methacrylate (10                                            mole %)/2-hydroxyethyl methacrylate                                            (10 mole %) copolymer                                                          HCFC-225              99%     by weight                                        Comparative Example 10                                                         2-(perfluoroisononyl) 1%      by weight                                        ethyl acrylate (50 mole %)/vinyl                                               acetate (30 mole %)/methyl                                                     methacrylate (10 mole %)/2-                                                    hydroxyethyl methacrylate                                                      (10 mole %) copolymer                                                          Pentafluoro propanol  99%     by weight                                        Comparative Example 11                                                         (Perfluoroalkyl**)ethyl                                                                              0.3%    by weight                                        acrylate (60 mole %)/methyl                                                    methacrylate (30 mole %)/                                                      hydroxyethyl methacrylate                                                      (10 mole %) copolymer                                                          (**The perfluoroalkyl group was a mixture of from C.sub.4 F.sub.9              to C.sub.10 F.sub.21, and C.sub.8 F.sub.17 was the main component.)            Ethyltrifluoro acetate                                                                               60%     by weight                                        Perfluorohexane       39.7%   by weight (*)                                    Note(*): This amount does not exceed 40% by volume.                            Comparative Example 12                                                         (Perfluoroalkyl**)ethyl                                                                              0.3%    by weight                                        acrylate (60 mole %)/methyl                                                    methacrylate (30 mole %)/                                                      hydroxyethyl methacrylate                                                      (10 mole %) copolymer                                                          (**The perfluoroalkyl group was a mixture of from C.sub.4 F.sub.9              to C.sub.10 F.sub.21, and C.sub.8 F.sub.17 was the main component.)            HCFC-123              50%     by weight                                        HCFC-141b             49.7%   by weight                                        ______________________________________                                    

In Table 2, there are comparably shown characteristics of the oil-repellent compositions in the above-mentioned ratios.

Evaluation of oil-repellency

Each oil-repellent composition was applied onto an acrylic substrate (Delpet 80N; Asahi Chemical Industry Co., Ltd.), and the oil-repellency was then evaluated at a contact angle by hexadecane.

Plastic resistance

In order to confirm that bad influences such as dissolution and swelling to general-purpose plastics were not present, a swelling test was made. As substrate materials to be used, there were selected PMMA (acryl), Delpet 80N (Asahi Chemical Industry Co., Ltd.), PC (polycarbonate), Panlight 1225 (Teijin Chemical Industry Co., Ltd.), ABS (acrylonitrile/butadiene/styrene copolymer), Saikorak EX120 (Ubc Salkon Co., Ltd.), POM (polyacetal), Juracon M90 (Polyplastic Co., Ltd.), Urethane rubber, Mirakutran E585 (Nippon Mirakutran Co., Ltd.) and natural rubber. Each substrate having a size of 25×100×3 was immersed in each oil-repellent composition for 1 hour, and weight changes after the immersion were then calculated. The substrates having a weight change of less than 0.1% by weight are represented by o, the substrates of from 0.1% by weight to 1% by weight are represented by Δ, and the substrates of 1% by weight or more are represented by x.

Flammability

The flammability was measured in accordance with JIS K2265 by the use of a tag sealing type automatic flash point test machine (ATG-4 type; Tanaka Science Instrument Co.. Ltd.).

Drying time

10 μl of each solvent composition were dropped on a slide glass, and a time which was taken till weight change was not observed any more was measured.

                                      TABLE 2                                      __________________________________________________________________________            Plastic Resistance    Oil-  Water-                                                                               Flash                                                                              Drying                                                 Rubber                                                                             Rubber                                                                             Repellency                                                                           Repellency                                                                           Point                                                                              Time                                                                               ODP                                  Acryl                                                                              PC ABS                                                                               POM A   B   [°C.]                                                                         [°C.]                                                                         [°C.]                                                                       [sec]                                                                              *1                            __________________________________________________________________________     Example 11                                                                            ◯                                                                      ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                      ◯                                                                      78    119   None                                                                               20  Absent                        Example 12                                                                            ◯                                                                      ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                      ◯                                                                      72    116   None                                                                               50  Absent                        Example 13                                                                            ◯                                                                      ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                      ◯                                                                      74    116   None                                                                               25  Absent                        Example 14                                                                            ◯                                                                      ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                      ◯                                                                      69    116   None                                                                               25  Absent                        Example 15                                                                            ◯                                                                      ◯                                                                     ◯                                                                     ◯                                                                      ◯                                                                      ◯                                                                      75    117   None                                                                               30  Absent                        Comp. Ex. 7                                                                           ◯                                                                      ◯                                                                     ◯                                                                     Δ                                                                            Δ                                                                            x   77    118   None                                                                               28  Present                       Comp. Ex. 8                                                                           ◯                                                                      ◯                                                                     ◯                                                                     Δ                                                                            Δ                                                                            x   77    117   None                                                                               30  Present                       Comp. Ex. 9                                                                           x   ◯                                                                     ◯                                                                     ◯                                                                      x   Δ                                                                            74    116   None                                                                               31  Absent                        Comp. Ex. 10                                                                          x   x  x  ◯                                                                      Δ                                                                            Δ                                                                            73    115   None                                                                               90  Absent                        Comp. Ex. 11                                                                          Δ                                                                            Δ                                                                           Δ                                                                           Δ                                                                            Δ                                                                            Δ                                                                            72    116   25  75  Absent                        Comp. Ex. 12                                                                          x   x  x  x   x   x   73    116   None                                                                               10  Present                       __________________________________________________________________________      Rubber A: urethane rubber                                                      Rubber B: Natural rubber                                                       *1: ODP: Ozone depletion potentials (ozone destruction coefficient)       

What is claimed is:
 1. A nonflammable liquid degreasing solvent consisting essentially of 40% by volume or more of a non-flammable perfluoro organic compound and 40% by volume or more of a flammable liquid organic compound. perfluoro organic compound.
 2. The solvent composition according to claim 1 wherein said perfluoro organic compound has a vapor pressure of 30 Tort or more at 25° C.
 3. The solvent composition according to claim 1 wherein said flammable organic compound has a solubility parameter of 7.5 or less.
 4. The solvent composition according to claim 1 wherein said flammable organic compound contains at least one selected from the group consisting of diethyl ether, diisopropyl ether, methyl tert-butyl ether, n-pentane, n-hexane, isohexane, isoheptane, isooctane and hexamethyldisiloxane.
 5. The solvent composition according to claim 1 wherein said perfluoro organic compound is at least one selected from the group consisting of perfluroalkanes, perfluorocycloalkanes and perfluoro cyclic ethers.
 6. The solvent composition according to claim 5 wherein said perfluroalkanes and perfluorocycloalkanes are C₅ F₁₂, C₆ F₁₄, C₇ F₁₆, C₈ F₁₈, C₆ F₁₂, C₇ F₁₄ and C₈ F ₁₆.
 7. The solvent composition according to claim 3 wherein said perfluoro cyclic ethers are selected from the group consisting of C₆ F₁₂ O, C₇ F₁₄ O and C₈ F₁₆ O.
 8. The solvent composition according to claim 1 wherein said flammable organic compound is at least one selected from the group consisting of ether compounds, alkanes and cycloalkanes.
 9. The solvent composition according to claim 8 wherein said ether compound is a compound represented by the formula

    R.sub.1 --O--R.sub.2

wherein R₁ is C_(n) H_(2n+1) or --Si(CH₃)₃, R₂ is C_(m) H_(2m+1) or --Si(CH₃)₃, and n and m meet 1≦n, m≦4 and 2≦n+m≦6.
 10. The solvent composition according to claim 8 wherein said alkanes and cycloalkanes are compounds represented by the formula

    C.sub.p H.sub.2p+2 and C.sub.q H.sub.2q

wherein p and q meet 5≦p and q≦8. 